This research proposal is designed to study prosody in autistic children s utterances to test for a relationship between impaired pragmatic language and impaired use of prosody. Prosody refers to the suprasgmental information in speech, including variations in pitch, amplitude and relative durations of sound and silence. This study will collect and analyze a database of speech samples elicited from children with autism, children with specific language impairment (SLI) and normally-developing children. Children will be asked to describe silent video presentations and answer questions regarding the video content. Specific tests of differences in the tonal structure (pitch) and metrical structure (durations) of prosody related to lexical, syntactic and pragmatic structure among these children will be performed. Autistic children are predicted to be relatively impaired in prosody related to pragmatics, but spared in prosody related to work and syntax, whereas SLI children are predicted to be relatively impaired in prosody related to words and syntax, but spared in prosody related to pragmatics. Finally, listener acceptability judgments of prosody will be compared to determine the aspects of prosody related to the clinical impression that prosody is unusual in autism. These analyses will provide insight to the diagnosis and remediation of autism and SLI as well as inform theories of normal language development.